The approaches described in this section may be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
One approach to distributing an electronic signal in a stackable device is to connect external wires to the each of the stackable devices. A problem with this approach is that the external wires are cumbersome and, in some cases, can lead to hazardous conditions; for example, the wires may present a tripping hazard. Another problem with the use of external wires is that their configuration requires expertise and is prone to error. For example, in many instances, only a limited number of certain devices can be connected together. If more than a preset number of devices are connected together, then the system will not function properly. For example, consider a computer that has limited capability to address memory on hard disk. If a human operator connects too many disk drives together and, thereby, more drive space than is addressable is added, the system will not function as intended. Alternatively, in some systems only a limited number of output devices can be driven by a particular signal output.
A second approach to distributing an electronic signal in a stackable device is to use a bus or a daisy chain. Either a bus or a daisy chain can involve wires that are internal to an encompassing case, but each still requires wires that are external to the stackable devices For example, a bus implemented as a ribbon cable connecting multiple disk drives is external to the disk drives, but internal to a computer case. Since the wires are external to the stackable devices, the approach still suffers the problems of cumbersome wires and expertise being needed to properly connect multiple devices to the bus or daisy chain.
Both of these approaches also suffer in that neither has a manner to simplify configuration, and specifically to simplify the limitation of devices that can be interconnected.
Therefore, given the discussion above, it is clearly desirable to have techniques that overcome the limitations discussed herein.